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Fricke gel dosimeters have great potential for three‐dimensional (3D) dose verification in radiation therapy; however, they suffer from time‐dependent ion diffusion after irradiation, severely affecting their stability and reliability. In this work, a pullulan‐based amphiphilic molecule was synthesized, characterized, and self‐assembled into nanogels. Nanogel structures were embedded into gel dosimeters to reduce the diffusion rates, and radiation‐sensitive nanogel‐incorporated Fricke hydrogel nanocomposites were prepared successfully. The results demonstrated that the diffusion coefficient of improved dosimeters was reduced to 0.125 ± 0.001 mm2 h−1, while maintaining the high optical dose sensitivity (0.0410 ± 0.0004 Gy−1 cm−1). It provides a powerful tool toward the practical application of 3D dosimeters. [ABSTRACT FROM AUTHOR]

The irradiation of tumors in radiotherapy requires accurate 3D dosimetry. The Fricke 3D dosimeters, which were considered to be high potential of application in 3D dosimetry, suffer from a reduced temporal integrity of dose distribution caused by Fe3+ ions diffusion. To overcome the drawback, we firstly synthesized a kind of amphiphilic molecules with critical micelle concentration of 0.45 g/L and hydrophile‐lipophile balance value of 10, then prepared multiple emulsions by self‐assembling those molecules in Fricke solution under liquid paraffin, and finally obtained Fricke hydrogel embedded with the multiple emulsions. The diffusion coefficient of Fe3+ ions in the embedded Fricke hydrogel was measured to be 0.17 mm2/h. The hydrogel dosimeter exhibits considerable potential for use in dose verification applications. [ABSTRACT FROM AUTHOR]

The Fe3+ diffusion in Fricke gel dosimeter, widely used for the measurement of accurate dose distributions in radiotherapy, results in a gradual blurring of the dose pattern with time after irradiation. In order to solve this issue, we embedded Fricke gel dosimeter with boron nitride nanosheets. The results show that the nanosheets-embedded gel dosimeter exhibited lower diffusion rate of Fe3+ ions (0.23 mm2 h−1) and a good response to γ irradiation in UV absorbance spectra. The hydrogen bond barriers between nanosheets and the gels were an important mechanism for the hindrance to Fe3+ diffusion besides the physical blocking of the Fe3+ motion by boron nitride nanosheets. This work will benefit understanding the mechanism for the limit on irons' diffusion and developing three dimensional Fricke gel dosimeter for the measurement of accurate dose distributions. [ABSTRACT FROM AUTHOR]

The diffusion of ferric ions is an important challenge to limit the application of Fricke gel dosimeters in accurate three-dimensional dose verification of modern radiotherapy. In this work, low-diffusion Fricke gel dosimeters, with a core-shell structure based on spatial confinement, were constructed by utilizing microdroplet ultrarapid freezing and coating technology. Polydimethylsiloxane (PDMS), with its excellent hydrophobicity, was coated on the surface of the pellets. The concentration gradient of the ferric ion was realized through shielding half of a Co-60 photon beam field size, and ion diffusion was measured by both ultraviolet-visible spectrophotometry and magnetic resonance imaging. No diffusion occurred between the core-shell pellets, even at 96 h after irradiation, and the diffusion length at the irradiation boundary was limited to the diameter (2–3 mm) of the pellets. Furthermore, Monte Carlo calculations were conducted to study dosimetric properties of the core-shell dosimeter, which indicated that a PDMS shell hardly affected the performance of the dosimeter. [ABSTRACT FROM AUTHOR]

With the widespread application of nuclear technologies, radiation dose measurement is important. Ferrous sulfate dosimeters are common chemical dosimeters, but their high detection limit and narrow dosimetry range limit their application in some fields. In this work, we introduce a novel dosimetry approach for ferrous sulfate dosimeters utilizing the fluorescence properties of gold nanoclusters (AuNCs) capped with histidine. The Fe2+ ions in the ferrous sulfate dosimeter are oxidized to Fe3+ ions during irradiation. The presence of Fe3+ ions results in the fluorescence quenching of AuNCs, establishing a correlation between the fluorescence intensity of the dosimeter and irradiation doses. The lowest detection limit of the fluorescence dosimeter was found to be 2 Gy. Moreover, the dose response of the dosimeter showed good linearity within the dose range of 2–400 Gy. The dosimetric sensitivity of the fluorescence dosimeter was 17.9% higher than that of ultraviolet–visible spectroscopy. The results indicate that the dosimetry method utilizing the fluorescence properties of AuNCs significantly improves the detection sensitivity and detection limit of the dosimeter. Our work provides a new dosimetry method for ferrous sulfate dosimeters that can be used in a wider range of irradiation situations. • Fluorescent probes are prepared utilizing nontoxic histidine as ligands. • The lowest detection limit of dosimeters is 2 Gy based on fluorescence dosimetry. • The fluorescence intensity of dosimeters is linear with radiation doses (2–400 Gy). • The detection sensitivity of fluorescence dosimeters improves by 17.9%. [ABSTRACT FROM AUTHOR]